Schema for `editor` / `editor_options` in front matter

[jmcphers]

In RStudio you can set this:

which results in this YAML in the front matter:

editor_options: 
  chunk_output_type: inline | console

Positron would like to use this, too, to help people set output options in a durable, per-document way. We should add it to the Quarto YAML schema so it can be autocompleted, validated, and documented.

See also:
https://github.com/rstudio/rstudio/blob/35fe7156201d8bdad9b18ca12d6b690124f00a5a/src/gwt/src/org/rstudio/studio/client/rmarkdown/model/RmdEditorOptions.java

[cscheid]

PR open at #14033.